Renewable energyRenewable energy is a source of energy that can never be exhausted.
We can obtain renewable energy from the sun (solar energy), from the water (hydropower), from the wind (windmills), from hot dry rocks, magma, hot water springs (geothermal) and even from firewood, animal manure, crop residues and waste (Biomass).

Theoretically, wind could produce enough energy to meet global demand. In 2006, however, less than one percent of global electricity consumption came from wind. Why such an imbalance?

Worldwide Importance and Future Prospects

Global installed wind capacity in 2006 was around 74 Gigawatts (GW), according to the World Wind Energy Association. This was more than one percent of global electricity consumption, but because installed capacity does not reflect actual production, its contributions to the global energy mix are less than that.

Wind energy capacity is expected to more than double between early 2007 and 2010. Growth will be driven by rapidly developing countries, such as India, Brazil, and China. Several offshore wind parks are being planned in northern Europe and North America. Improving efficiency and falling costs of turbine production and installation will make wind power more price competitive.

Global Resources and Producers

Global land and near-shore wind resources are around 72,000 GW, or five times the world's current energy use, according to a study at Stanford University. But sites convenient for wind power production are limited by factors such as land use for agriculture or living, distance to consumers, and technology. Experts from the Intergovernmental Panel on Climate Change estimate that only four to ten percent of given resources could be used in an economically viable way.

An entirely wind-powered economy is thus not yet possible. Global growth in wind power, however, is still tremendous. In 2005, markets grew by 41 percent. The value of new generating equipment installed in 2006 was about 18 billion euros.

Energy Output

The amount of wind energy generated depends mostly on the size, height, type, and location of a wind turbine. Some small turbines, such as those fixed on a sailboat, can generate as little as a few hundred watts - enough to power a few light bulbs. On the other side of the spectrum are the large, utility-scale turbines like the Vestas V90 that produces 3 MW. According to the manufacturer, these turbines produce in 2-3 hours the electricity that an average European family consumes in one year. The Enercon E126 turbines installed in Germany in late 2007 will produce 6MW each, making it the most powerful turbine on the market.

Most wind power turbines are still installed on land, but the future could lie offshore. Wind speeds over oceans are on average twice as high as over land, making offshore wind parks an interesting alternative, but technically more challenging alternative.